Interpretive Summary: One goal of sustainable agricultural systems is to maximize the use of nutrients in cattle manure while minimizing its adverse environmental impacts - including the transfer of bacterial pathogens or excess nutrients within watersheds. Cattle manure from animals fed distiller’s grains has different physical, nutrient and microbial qualities compared to manure from animals fed traditional corn finishing diets, including higher dissolved and total phosphorus, and greater concentrations of pathogenic bacteria like E. coli O157:H7. This study was conducted to determine if animal diet affects how fecal bacteria and viruses are transported in runoff when cattle manure is applied to agricultural fields as a nutrient source. Our results indicate that the animal’s diet significantly affects how selected viruses are transported in runoff from the fields, following land application. The majority of the manure-borne bacteria remained on the plots, even after three large rainfall events. The number of bacteria and viruses that transported in runoff depended upon the amount of manure that was applied, but no significant differences were found between plots where the manure was tilled into the soil, compared to no-till plots.

Technical Abstract:
Manure from cattle fed distiller’s grain or corn diets was land-applied to fields and subjected to rainfall simulation tests. Manure was added at four rates on till and no-till plots. Correlations between microbial transport and runoff-characteristics were identified. Results indicate diet affects phage but not bacterial transport from manure-amended fields.